The Palestinian militant group Hamas, meanwhile, said it would join the cease-fire declared by Palestinian leader Yasser Arafat, and pledged to stop attacks in Israel as of midnight (5 p.m. EDT).

A statement by Hamas and Arafat's Fatah group said Israel would be given a chance to show that it has stopped its policy of assassinations and destruction.

Hamas took responsibility for a suicide bomb attack Friday night that killed 20 young Israelis in front of a Tel Aviv disco, and its compliance with Arafat's cease-fire call is seen as vital to its success. However, the other violent militant group, the Islamic Jihad, was not at the meeting where the statement on the cease-fire was issued.

West Bank's powerful security chief Jibril Rajoub pledged a "100 percent effort" Monday to enforce a cease-fire to end eight months of fighting.

Diplomatic efforts persisted, meanwhile, to end the fighting that has killed hundreds and paralyzed the decade-long effort to bring peace to the Holy Land.

Eighteen Palestinians were injured Monday in Gaza, four critically, hospital officials said. Two were shot in the head. One Israeli officer and two soldiers were slightly injured, the army said.

Each side blamed the other for the three-hour gunbattle.

Palestinian witnesses said Israeli soldiers fired rockets on Palestinians from the Rafah refugee camp. Israeli military officials said the Palestinians opened fire first with anti-tank grenades during a routine patrol to repair a fence.

The battle reversed the dramatic drop-off in shooting incidents following Arafat's call Saturday for a cease-fire. Arafat was under tremendous international pressure to call a truce after the suicide bombing of the disco.

Prior to Monday's firefight, the army reported six other shooting attacks by Palestinians since Saturday.

Since the fighting erupted last September, 484 people have been killed on the Palestinian side and 108 on the Israeli side.

Israeli Prime Minister Ariel Sharon said he was considering creating an armed buffer zone between Israel and the West Bank to prevent suicide bombers from entering Israel.

The daily Haaretz reported that the army had decided to create and patrol a zone east of the line that marks Israel's frontier with the West Bank before the 1967 Mideast war. A majority of the roads in the zone would be blocked, and Palestinians inside it would be prevented from traveling outside their villages after nightfall, Haaretz said.

The army did not respond to requests seeking comment on the report. However, a senior security source, speaking on condition of anonymity, said there was no way to completely prevent infiltrations along the West Bank border.

"In terms of the security area," Sharon said he was speaking of a zone and not a line. Meanwhile, Powell instructed his new envoy, William Burns, to remain in the region. CIA director George Tenet was also expected, Israeli Foreign Ministry spokesman Emanuel Nachshon said.